linux-kernel - Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail

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Message-ID: <3700f05f-2411-4422-972f-f3df690efb84@collabora.com>
Date:   Tue, 5 Dec 2023 11:22:46 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Doug Anderson <dianders@...omium.org>,
        Chen-Yu Tsai <wenst@...omium.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Wolfram Sang <wsa@...nel.org>,
        Benson Leung <bleung@...omium.org>,
        Tzung-Bi Shih <tzungbi@...nel.org>,
        chrome-platform@...ts.linux.dev, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Johan Hovold <johan@...nel.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        andriy.shevchenko@...ux.intel.com, Jiri Kosina <jikos@...nel.org>,
        linus.walleij@...aro.org, broonie@...nel.org,
        gregkh@...uxfoundation.org, hdegoede@...hat.com,
        james.clark@....com, james@...iv.tech, keescook@...omium.org,
        rafael@...nel.org, tglx@...utronix.de,
        Jeff LaBundy <jeff@...undy.com>, linux-input@...r.kernel.org,
        linux-i2c@...r.kernel.org
Subject: Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark
 touchscreens and trackpads as fail

Il 04/12/23 17:50, Doug Anderson ha scritto:
> Hi,
> 
> On Sun, Dec 3, 2023 at 10:59 PM Chen-Yu Tsai <wenst@...omium.org> wrote:
>>
>> On Sat, Dec 2, 2023 at 8:58 AM Doug Anderson <dianders@...omium.org> wrote:
>>>
>>> Hi,
>>>
>>> On Tue, Nov 28, 2023 at 12:45 AM Chen-Yu Tsai <wenst@...omium.org> wrote:
>>>>
>>>> @@ -44,6 +46,7 @@ trackpad2: trackpad@2c {
>>>>                  reg = <0x2c>;
>>>>                  hid-descr-addr = <0x0020>;
>>>>                  wakeup-source;
>>>> +               status = "fail-needs-probe";
>>>
>>> While doing this, you could also remove the hack where the trackpad
>>> IRQ pinctrl is listed under i2c4.
>>
>> Sure. I do think we can do away with it though. According to at least one
>> schematic, the interrupt line has pull-ups on both sides of the voltage
>> shifter.
>>
>> BTW, The touchscreen doesn't have pinctrl entries. This has pull-ups on
>> both sides of the voltage shifter as well.
> 
> I dunno if the convention is different on Mediatek boards, but at
> least on boards I've been involved with in the past we've always put
> pinctrl entries just to make things explicit. This meant that we
> didn't rely on the firmware/bootrom/defaults to leave pulls in any
> particular state. ...otherwise those external pull-ups could be
> fighting with internal pull-downs, right?
> 

MediaTek boards aren't special and there's no good reason for those to rely on
firmware/bootrom/defaults - so there is no good reason to avoid declaring any
relevant pinctrl entry.

Cheers,
Angelo